pic hex to asm
For 16f series of PIC IC you have a software(free) picdisasm. This is a Windows version.Very easy to use. Can be recompiled immediately on MPLAB. You can even check if the program will fit into a particular IC, if you dont know the exact ic. For 18 series a dos version is available picdis18w. Oshon software pic18 simulator ide will also create the disassembly (with or without opcodes).
All versions create label automatically.
If you get a listing with line nos and opcodes, import the file into excel, drop the two columns which you do not need, copy the balance contents to a notepad, rename it as asm and open in Mplab.
But for any disassembly, as said earlier by others, you need to know how the PIC functions to make any useful asm program.
If you cannot find the softwares above, just pm me.